Ion

An electrically charged atom (Na+, Al+3, CL-, S-2) or group of atoms known as “radicals” (NH4+, SO4-2, PO4 3).

Ionization

Dissociation of ions in anaqueous solution (e.g., H2C03 – H+ + HCO3- or H2O – H+ OH).

Jacking

The actual pushing of pipe or casing in an excavated hole. This is usually done with hydraulic cylinders (jacks), but has been done with mechanical jacks, air jacks and just about anything else that man could imagine.

Jacking Force

The total force required to overcome the face pressure component and the frictional resistance component along the pipe so as to allow forward movement of the MTBM and the trailing pipe string.

Jacking Frame

A structural component that houses the hydraulic cylinders used to propel the microtunneling machine and pipeline. The jacking frame cradles the MTBM and jacking pipes, and serves to distribute the thrust load to the pipeline and the reaction load to the shaft wall or thrust block.